Methods: 40 samples were prepared with class II cavities in mesial and distal sides of human molar teeth and were divided into four groups. Group1: 3mm buccolingual width cavity (to be known as the smaller cavity) filled with Tetric Bulk Fill composite. Group2: 6 mm buccolingual width cavity (larger cavity) filled with Tetric Bulk Fill composite. Group3: 3 mm buccolingual width cavity filled with X-tra base composite. Group4: 6 mm buccolingual width cavity filled with X-tra base composite. Thereafter, the specimens were thermally stressed for 500 cycles in water bath at 5 and 55°C, protected with nail polish, colored with 1% methylene blue dye, cut into sections, and finally evaluated.
Results: The data were submitted to ANOVA and the results showed the highest degrees of microleakage in larger cavity of X-tra base among four groups and there was a significant statistical difference (P=0.012) between larger and smaller cavity of X-tra base (Groups 3 and 4) while there was no statistical difference between two cavity sizes of Tetric-filled groups.
Conclusions: The recent advancements in restorative dentistry have come up with a variety of achievements which need a precise and delicate approach to make the finest choices. According to this experiment, Tetric bulk fill composite lies in a strongly superior position compared with X-tra base composite when it comes to microleakage and polymerization shrinkage.